Fig.22: refining panel borders: check fig. 23 to see where i added edges to keep geometry the way i wanted

Next step is to detach all the various panels as single objects. To achieve this, just go under "polygons property" (polygon sub-object mode) in the poly panel and use "select by material ID". Select the various ID and each time hit the "detach" button, deselecting "detach as clone" and "detach to element" in the panel that pops up. Name the various parts properly. Now it's time to add thickess to the panels: the way i choose for this is selecting a panel mesh, add a "solidify" (look for it on the "max 4" section of maxplugins.de) modifier and set the thickness to a reasonable value (for me 0.5). I then collapse the stack beck to editable poly (right click on the object and "convert to..."). Now i start deleting all the interior faces (which will not be seen in the final renders, so no reason at all to increase the poly count by leaving them there), as well as the faces in the middle line between a mirrored mesh. Do not delete interior face on glasses (ie windshield) because we want correct thickness for refractions. An example of what you will achieve with all the panels is shown on the bonnet in Fig. 19 (with interior faces still there) and Fig. 20 (with deleted faces). I then select all the edges giving thickness (just select 1 edge and then hit "ring") and connect them once to get a proper edge smoothness for the borders (Fig. 21). You will notice that some panels are not keeping the shape they are supposed to. This is because the poly topology is wrong. Start cutting the mesh properly to keep curvatures the way you want (Fig. 22 and Fig. 23 show the border of some panels: you can see where i added edges to keep proper geometry ). Do this to all the panels.

When you need to modify the position of vertices on the boundary of a panel, you have to move the vertices of all the surronding panels as well, to keep things right: what i do is attach the panels back together, select the vertices, move them, then go in "element" subobject mode, select the various panels and detach them again (if needed). You can do this as many times as you want, or just keep everything detached and move vertices accoirdgingly, just choose a method you fell comfortable with.

After all this process, you can have a look at the smoothed version of the car: see how all the panels have a nice smooth border (Fig. 24). Take a look at the unsmoothed wireframes if you are confused (Fig. 25) and try to get a similar cage. In Fig. 25 you also see 2 areas where i had to cut the mesh to get proper "tight" curvatures (almost 90°).

Onto with further detailing: adding the headlights.
Adding headlights was a bit time consuming (getting the shape right was the main problem). First select the polygons as shown in Fig. 26, then bevel them twice and then extrude them inwards, just look at the figure to see how to do this.
Now it's just a matter of moving and welding vertices, as well as some more edge cutting, to get the shape right. If you don't know how to do it, just look at Fig. 27 and try to get a similar mesh with correct smoothness once you activate NURMS subdivisions.When i add edges in a particular place, i try not to break up loops and rings, thus i add edges on the whole panel so that i keep my quad scheme in the mesh. This can lead to some problems (ie in Fig. 25) because you get extra-detail where you don't need it: it's just a matter of keeping vertices properly positioned so the mesh remains smooth and clean.

As you can see, the more i progress with the modeling the more i get differences in the topology of adiacent panels (ie the bonnet edge is no more coincident with the door panel in Fig. 25). This is not a problem as long as the smoothed version leads to aligned panels. Anyway try to keep topologies similar whenever you can (your life gets really easier this way).

To model the headlight glass i did this: select the headlight and go in "edge" subobject mode (Fig. 28). Loop select the boundary of the new panel to be created and hit "create shape from selection" and select "linear" in the pop up. Now select the newly created shape, name it "headlight" and convert to poly. This way you have a bunch of vertices in the right positions. Go in "polygons" subobject mode and hit "create". Pick all the vertices one by one counterclockwise: a new face is created.

Now just connect vertices and cut edges to get a proper mesh (pretty intuitive, anyway look at Fig. 28 to see how i did it). As previously done with the other panels, add a "solidify" modifier to give thickness to the glass: do not delete interior faces this time, as we obviously want a glass to refract correctly. Activate NURMS subdivisions on the body and the glass to be sure they fit correctly, and adjust vertices if needed.

Fig.23: refining panel borders: i used the "cut" tool to add egdges near the borders of the various panels

Fig.24: smooth panels: the result of panel smoothing

Fig.25: wireframe so far: take a look where i added edges to get the right shapes

Fig.26: the headlights: step by step here ;-)

Fig.27: the headlights: move and weld vertices to get this!

Fig.28: the headlight's glass: follow the steps to model the glass!

Fig.29: the headlight's smaller panel: just cut and rebuild

As you can see from reference photos, there's a small plastic panel over the headlight, which at first i didn't consider. Anyway this is easyly builded by cutting the headlight glass panel (i used "quickslice" in vertex mode to get a new row of edges where the new panel will be detached, then i selected the smaller panel faces and detached them from the headlight glass), creating faces on the cut area (in fact you get a hole on the border when you detach the panel but it is easily capped by creating faces to get a closed mesh) and adding edges on the borders to retain proper curvatures. You can take a look at the wireframe and the smoothed (NURMS) version in Fig. 29.

The inner part of the headlight (the actual lights) are modeled as separate components: they are very easy as we don't need to be very precise here: i just modeled a rectangular spline and 2 more spline (a circle and a rectangle), converted all to spline, connected them and extruded. Then i placed a sliced box (meshsmoothed) and a half sphere in the holes (inverting the normals with the "normal" modifier), and covered them with a thin box and a thin cylinder (glass material). You can refer to the image to see the final result.

That's it for this section. In next (and last) one, we will cut holes for the air intakes, model the front bumper, cut holes for the exausts and model them, cut holes for the taillights and model them, add real tyres, rearview mirrors, an antenna and the interiors (engine, seats, wheel, various stuff). So, if you are ready you can proceed.